A non-aqueous-secondary-battery represented by a lithium ion secondary battery has been widely used as a power source of a portable electronic apparatus such as a notebook computer, a mobile phone, a digital camera, or a camcorder. In addition, in recent years, it has also been investigated to apply such a battery to an automobile or the like in view of characteristics of high energy density.
An outer package of the non-aqueous-secondary-battery has been simplified according to miniaturization and light weight of the portable electronic apparatus. A stainless steel battery can has been initially used as the outer package, but an outer package of an aluminum can has been developed, and currently, a soft outer package of an aluminum laminate package has been also developed. In a case of using the aluminum laminate soft outer package, the outer package is flexible, and accordingly, a space may be formed between an electrode and a separator due to charging and discharging, and this may lead to a technical problem of a short cycle life. In order to solve such a problem, a technology of adhering the electrode and the separator is important and a number of technical proposals have been made.
As one proposal, a technology of using a separator in which a porous layer (hereinafter, also referred to as an adhesive porous layer) formed of a polyvinylidene fluoride resin is formed on a polyolefin microporous membrane which is a separator of the related art, has been known (for example, see PTL 1 to PTL 4). When the adhesive porous layer is subjected to hot pressing to be overlapped with an electrode in a state of including an electrolyte, the adhesive porous layer can cause the electrode and the separator to excellently adhere to each other and has a function as an adhesive. Therefore, it is possible to improve the length of the cycle life of the soft package battery.
In addition, when manufacturing the battery using a metal can outer package of the related art, the electrode and the separator are wound in a state of being overlapped with each other to manufacture a battery element, this element is enclosed in the metal can outer package with the electrolyte, and the battery is manufactured. Meanwhile, when manufacturing the soft package battery using the separators disclosed in PTL 1 to PTL 4, the battery element is manufactured in the same manner as the case of the metal can outer package described above, this is enclosed in the soft outer package with the electrolyte, a hot pressing step is finally applied thereto, and the battery is manufactured. Accordingly, when using the separator including the adhesive porous layer, it is possible to manufacture the battery element in the same manner as the case of the battery of the metal can outer package described above, and accordingly, it is not necessary to make a lot of modifications to the manufacturing step of the metal can outer package battery of the related art.